K24 turbo fitting

I'm installing a hybrid turbo on a 200Q20V for someone. Turbo is modified K26 to look like "k25" - don't ask me for details, I don't know, only that the intake impeller was clipped, or something to that effect.
My question pertains to a fitting that was on the k24 but not on the modded k26. This fitting is some type of pressure/vacuum port on the front/snail part of the turbo. On the modified turbo, there is a boss that could be tapped if necessary.
This port on the k24 went to a four way tee or "cross". The top of the cross is a solenoid. The bottom goes to the fitting in question. One arm of the cross goes to the lower wastegate port and the other arm goes to the backside of the turbo intake hose.
What is this fitting for and how critical to use? Unless there is some reason, I am just going to block off the bottom of the "cross" and hope it'll be just fine without.
Ben